Hexagrammidae, the greenlings, is a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of marine

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

es belonging to the

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

Cottoidei Cottoidei is a suborder of ray-finned fishes which, according to the 5th edition of ''Fishes of the World'', is placed within the order Scorpaeniformes, alongside the scorpionfishes, flatheads, eelpouts, sticklebacks and related fishes. Taxon ...

in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Perciformes Perciformes (), also called the Acanthopteri, is an order or superorder of ray-finned fish in the clade Percomorpha. ''Perciformes'' means " perch-like". Among the well-known members of this group are perches and darters ( Percidae), and als ...

. These fishes are found in the

North Pacific Ocean North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography. Etymology The word ''north'' ...

Taxonomy

Hexagrammidae was first proposed as a family in 1888 by the American

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

David Starr Jordan David Starr Jordan (January 19, 1851 – September 19, 1931) was the founding president of Stanford University, serving from 1891 to 1913. He was an ichthyologist during his research career. Prior to serving as president of Stanford Universi ...

. The 5th edition of ''

Fishes of the World ''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...

'' classifies this family as the only family in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

Hexagrammoidea within the suborder Cottoidei of the diverse order Scorpaeniformes. Other workers have found that if the Scorpaeniformes, as delimited in ''Fishes of the World'', is not included in the

it renders the Perciformes

paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...

. These workers retain the Cottoidei as a suborder within the

while reclassifying Hexagrammoidea as the

infraorder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between Family_(biology), family and Class_(biology), class. In biological classification, the order is a taxonomic rank used in the classific ...

Hexagrammales. The family

Zaniolepididae The Zaniolepididae is a Family (biology), family of marine ray-finned fishes classified within the suborder Cottoidei of the Order (biology), order Perciformes. They are found in the North Pacific Ocean. Taxonomy ''Zaniolepididae'' was first pro ...

has been included within the Hexagrammidae, as the subfamilies

Zaniolepidinae ''Zaniolepis'', the combfishes, is a genus of marine ray-finned fish, it is one of two genera in the family Zaniolepididae. These fishes are native to the eastern Pacific Ocean. ''Z. frenata'' that was a source of food to the Native American in ...

and

Oxylebiinae The painted greenling (''Oxylebius pictus'') is a species of marine ray-finned fish belonging to the family Zaniolepididae, which includes this species and the combfishes. It is endemic to the northeast Pacific Ocean. It is the only species in t ...

, but ''Fishes of the World'' and Betancur ''et al'' classify these taxa as distinct from the Hexagrammidae. Placing these two families in their own monotypic superfamilies was originally proposed in 1994 by Gento Shinohara.

Subfamilies and genera

Hexagrammidae contains the following subfamilies and genera: * Subfamily

Ophiodontinae ''Ophiodon'' is a genus of marine ray-finned fishes belonging to the family Hexagrammidae, the greenlings. It is found in the northeastern Pacific Ocean. Species ''Ophiodon'' has one extant species and one known extinct species: * '' Ophiodon e ...

Jordan & Gilbert, 1883 ** Genus ''

Ophiodon ''Ophiodon'' is a genus of marine ray-finned fishes belonging to the family Hexagrammidae, the greenlings. It is found in the northeastern Pacific Ocean. Species ''Ophiodon'' has one extant species and one known extinct species: * '' Ophiodon e ...

'' Girard, 1854 * Subfamily

Hexagramminae ''Hexagrammos'' is a genus of marine ray-finned fishes belonging to the family Hexagrammidae, the greenlings. These fishes are found in the north Pacific Ocean. Taxonomy ''Hexagrammos'' was first proposed as a monospecific genus in 1810 by the G ...

Jordan, 1888 ** Genus ''

Hexagrammos ''Hexagrammos'' is a genus of marine ray-finned fishes belonging to the Family (biology), family Hexagrammidae, the greenlings. These fishes are found in the north Pacific Ocean. Taxonomy ''Hexagrammos'' was first proposed as a monospecific genu ...

'' Tilesius, 1810 *Subfamily

Pleurogramminae ''Pleurogrammus'' is a genus of ray-finned fishes belonging to the family Hexagrammidae, the greenlings, known as Atka mackerels. These fishes are found in the northwestern Pacific Ocean. Taxonomy ''Pleurogrammus'' was first proposed as a genus ...

Rutenberg, 1954 ** Genus ''

Pleurogrammus ''Pleurogrammus'' is a genus of ray-finned fishes belonging to the Family (biology), family Hexagrammidae, the greenlings, known as Atka mackerels. These fishes are found in the northwestern Pacific Ocean. Taxonomy ''Pleurogrammus'' was first pr ...

Gill A gill () is a respiration organ, respiratory organ that many aquatic ecosystem, aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow r ...

, 1861

Characteristics

Hexagrammidae have cirri but do not have ridges or spines on their heads, They have between one and five

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

s and may have

cycloid In geometry, a cycloid is the curve traced by a point on a circle as it Rolling, rolls along a Line (geometry), straight line without slipping. A cycloid is a specific form of trochoid and is an example of a roulette (curve), roulette, a curve g ...

ctenoid scale A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as w ...

s. There is a single

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

which is notched and contains between 16 and 28 spines and 11 and 30 soft rays. There is a single spine and 5 soft rays in the

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

. The front nostril on each side of the snout is well developed but the rear nostril may be absent or if it is there it is merely a small pore. The

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

may have upn to 3 spines, or there may be no spines, and 6 or 7 soft rays. There is no swimbladder. The largest species is the lingcod (''Ophiodon elongatus'')which has a maximum published

total length Fish measurement is the measuring of individual fish and various parts of their anatomies, for data used in many areas of ichthyology, including taxonomy and fishery biology. Overall length Standard length (SL) is the length of a fish measured f ...

of but typically they are or less in length.

Distribution and habitat

Hexagrammidae is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the North Pacific Ocean where they are found in the subarctic and temperate regions, with a single species, the whitespotted greenling '' Hexagrammos stelleri'', being found in the Arctic Ocean too. They occur from the

intertidal zone The intertidal zone or foreshore is the area above water level at low tide and underwater at high tide; in other words, it is the part of the littoral zone within the tidal range. This area can include several types of habitats with various ...

to as deep as but most are found in waters of depths of less than on the

continental shelf A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an islan ...

Biology

Hexagrammidae greenlings are

demersal fish Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes (the demersal zone).Walrond Carl . "Coastal fish - Fish of the open sea floor"Te Ara - the Encyclopedia of New Zealand. Updated 2 March 2009 They oc ...

es, except for the

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

''Pleurogrammus'', and they feed on crustaceans, polychaetes, small fishes and fish eggs.

Utilization

Hexagrammidae greenlings are fished for, the coastal species are fished for using hook and line and

spears A spear is a polearm consisting of a shaft, usually of wood, with a pointed head. The head may be simply the sharpened end of the shaft itself, as is the case with fire hardened spears, or it may be made of a more durable material fastened to t ...

and in the late 20th and early 21st centuries the kelp greenling (''Hexagrammas decagrammus'') has become a target of a commercial fishery, while historically the lingcod (''O. elongatus'') and the

atka mackerel The Atka mackerel (''Pleurogrammus monopterygius'') is a mackerel in the family Hexagrammidae. Atka mackerel are common in the northern Pacific Ocean, and are one of only two members of the genus ''Pleurogrammus'' – the other being the Arabes ...

s of the genus ''Pleurogrammus'' have been the most targeted species.

References

* * {{Authority control Perciformes families * Taxa named by David Starr Jordan